The choice of whether to use a condom or not is influenced by a number of factors. These include: a woman's desire to get pregnant, one's experience using other methods of contraception, and the relationship of the partners, Copen said.

"People who say they are dating casually use more condoms than people who say they are co-habitating or engaged," she said.

Most people who use condoms say they use them to prevent pregnancy and avoid getting an STD, Copen said.

"We have much better methods of birth control than a condom. If people don't want to have a baby, they should be using a more effective method," said Dr. Jill Rabin.

"Sex can be wonderful, but I don't know any climax that's worth the heartache of an unwanted pregnancy," said Rabin. She is co-chief of the division of ambulatory care in the Women's Health Programs-PCAP Services at Northwell Health in New Hyde Park, N.Y.

But condoms do have a role in preventing STDs, Rabin said. Often people don't know they have an STD until it's too late and they are infertile or sick, she said.

"We know that condoms can protect against many STDs," Rabin said. "So why would you deliberately place yourself in a position to get hepatitis B or C or HIV?

For the Aug. 10 report, Copen collected data on condom use among men and women aged 15 to 44 from the 2011-2015 U.S. National Survey of Family Growth. The findings were compared with surveys from 2002 and from 2006 to 2010.

The researchers interviewed 11,300 women and more than 9,300 men about condom use between September 2011 and September 2015.

During that time, about 24 percent of women and 34 percent of men used a condom during their last sexual intercourse. That's an increase for men since 2002, when about 30 percent reported using a condom, Copen said.

Among those who used condoms, nearly 60 percent of women and 56 percent of men said condoms were the only means of contraception used in the past year.

Another 25 percent of women and 33 percent of men used condoms plus hormonal methods such as birth control pills or implants. Fifteen percent of women and 10.5 percent of men used condoms plus nonhormonal contraception.

Copen also found that during past month intercourse, 18 percent of women and nearly 24 percent of men used a condom every time.

Nearly 7 percent of women who used a condom in the past month said the condom broke or fell off during intercourse or withdrawal. Nearly 26 percent said they used a condom only part of the time during intercourse, Copen said.

Dr. Dennis Fortenberry is a professor of pediatrics at Indiana University School of Medicine. "Although the overall proportions of condom use are relatively small, there are several positive aspects of the data," he said.

First, the overall proportion of condom use has been stable during recent years, without large changes in use across the U.S. population, said Fortenberry, a board member of the American Sexual Health Association.

"In addition, condom use is quite high among younger, sexually active populations, where STDs and pregnancy are important and where access to other means of prevention may be limited," he said.

The relatively high frequency of condoms that break or fall off suggests the need for continued public health education and training, he said.

"Although condoms will never solve all of the STD and pregnancy prevention needs of a diverse population, they remain an accessible and low-cost technology necessary for comprehensive public health prevention approaches," he added.